Horizontal lines are parallel to the horizon or parallel to level ground. They have a slope of zero and are parallel to the x-axis on a graph. Vertical lines are perpendicular to the horizon, parallel to the y-axis on a graph and have undefined slope.
Know MoreThe term "horizontal" derives from the Latin "horizontem" which means "flat." The term "vertical" derives from the Latin "vertex," which means "highest point."
The slope of a line refers to the change in the rise, or y-value, divided by the run, or the change in x-value. Because a horizontal line does not change in y-value with changes in x-value, its slope may be calculated as zero divided by any number. This results in a slope of zero. For vertical lines, the slope equation leads to a division by zero, which is undefined.
Learn more about ShapesContour lines do not ever cross one another because each line represents a different elevation on a topographic map. However, contour lines may merge in the case of a vertical cliff.
Full Answer >The number of lines of symmetry a triangle has depends on the type of triangle. An equilateral triangle has three lines of symmetry, while an isosceles has one line of symmetry, and a scalene triangle has none.
Full Answer >Circles have an infinite number of lines of symmetry. Any line that bisects a circle through its center is a line of symmetry. Circles are the only Euclidean shape with this property.
Full Answer >A regular pentagon has five lines of symmetry. An irregular pentagon, with non-equal side lengths and internal angles, may or may not have any lines of symmetry.
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